Adjust CONTRIBUTING.md for new docs

Author: raucao

CONTRIBUTING.md

@@ -1,9 +1,12 @@
-Contribution Guidelines
-=======================
+Contributing
+============
 
-TODO
-----
+We maintain a Contributing section for both new and seasoned contributors in
+our docs. Read the hosted version at
+https://remotestoragejs.readthedocs.io/en/latest/contributing.html or find the
+RST files in the ``doc/`` directory of this repo.
 
-* Write welcome paragraph
-* Link to new docs' contribution section
-* Link to other useful places, like wiki, forums, IRC
+There's a section about [our GitHub
+workflow](https://remotestoragejs.readthedocs.io/en/latest/contributing/github-flow.html),
+containing useful tips and help for making collaboration easier and our Git
+history more useful.